The present invention relates to heat sinks which are to be used for semiconductor devices or like heat generating articles as attached to the heat sink or to be attached to electronic devices having a heat generating article incorporated therein for dissipating the heat generated by the article.
The term xe2x80x9caluminumxe2x80x9d as used herein and in the appended claims includes pure aluminum, commercial aluminum containing traces of impurities and aluminum alloys. The term xe2x80x9cfrontxe2x80x9d refers to the front side of the fins.
Heat sinks comprising at least one row of many rectangular tonguelike fins formed on one surface of a heat dissipating base plate include those already widely known wherein each of the fins is bent forward at the entire outer end portion thereof to form a curl portion so as to confine the height of the fin to a predetermined tolerance range and to prevent cutting of the hand.
The curl portions are formed by using a cutting tool device which comprises a slider movable forward and rearward and provided at its lower end with a cutting tool having a cutting face, and a curl forming member attached to the upper end of the slider and projecting forward for guiding the outer end of the fin produced by cutting to a raised form and acting to extend upward, by coming into contact with the fin end so that the fin end portion is bent forward.
However, since the fin produced by cutting to the raised form is rectangular, the horizontal straight outer end is brought in its entirety into striking contact with the lower surface of the curl forming member at a time. Consequently, the fin is likely to deform by buckling, while the base parts of opposite ends of the curl portion are positioned at opposite side edge corners of the fin and are therefore likely to wound the hand as by cutting. Thus, the fins still remain to be improved to ensure safety.
An object of the present invention is to provide a heat sink having fins which are unlikely to deform by buckling when bent to form curl portions and which are also free of the likelihood of injuring the hand as by cutting.
The present invention provides a heat sink comprising at least one row of many tonguelike fins formed on one surface of a heat dissipating base plate, each of the fins having a circular-arc outer end, a midportion only of the entire circular-arc outer end portion being bent forward into a curl portion, the end portion having opposite side parts other than the midportion and remaining unbent as arcuate portions. The curl portion can be formed without causing deformation of the fin due to backling and obviates the likelihood of cutting the hand to ensure safety.
The present invention will be described below in greater detail with reference to the accompanying drawings.